Currently I am using an iPod touch and an Apple bluetooth keyboard as my mobile workspace. In my opinion, nothing can replace the computer at my home office so there is no point trying. Traditionally, the concept of a mobile computing device is a laptop, which is just a slim down version of a desktop. The most important thing about a mobile workspace is, well, mobile. Laptops are big, in fact some are huge and heavy. But when you make them smaller, like netbooks, they become very difficult to use (small keyboard, small trackpad, etc) because all the softwares on laptops are designed for desktops. That's why I dislike the idea of bring a laptop with me. With the iPod Touch and Apple keyboard combo, I can solve both problems. I can have a small, hence mobile, device with me (this thing is smaller than my hand) while maintaining usability. The Apple keyboard is a full size keyboard and since the iPod Touch has a touchscreen, I don't even have to worry about the mouse/trackpad. It is true that the iPod Touch cannot perform a lot of the task that a laptop can, but, as I mentioned before, the point of a mobile workspace is not to replace the main office, but to augment it. If the task that you need to complete is so important that you need a laptop to do it, maybe you should do it in a quite environment like your office, and not out on the street with all those distractions